It’s easy to say you’re against “endless wars.” Who, after all, is in favor of them? That’s why both President Trump and his Democratic opponents endlessly promise to end the endless wars. But Sen. Elizabeth Warren (D-Mass.) was on to something during the Democratic debate in Des Moines last week when she said: “Everyone on this stage talks about nobody wants endless war. But the question is, when and how do you plan to get out of it?” Bingo. Turns out it’s much easier to talk about ending endless wars than actually doing so.

Remember that in 2015 President Barack Obama also proclaimed “I do not support the idea of endless war,” and he actually tried to end the U.S. involvement in Iraq. But the U.S. troop pullout in 2011 created a security vacuum that allowed the Islamic State to rise from the ashes of al-Qaeda in Iraq, a terrorist group that had been all but defeated. With the Islamic State carving out a terrorist empire and beheading American hostages on television, Obama decided in 2014 to send U.S. troops back to Iraq — and there they have remained.

Obama’s attempt to end the war in Afghanistan was similarly ill-starred. He initially increased U.S. troop strength in Afghanistan to 100,000 with the intention of drawing down to close to zero by 2017. But, mindful of the lesson of Iraq and worried about the precarious security situation, Obama still had 8,400 U.S. troops in Afghanistan by the time he left office.

Trump has been even more vociferous than Obama about bringing troops “home from the ridiculous & costly Endless Wars” — and yet the total number of U.S. forces in the Middle East has gone up over the past year, to roughly 65,000 personnel. Trump twice announced a withdrawal from Syria and twice rescinded it. Having failed so far to reach a peace deal with the Taliban, Trump now has more troops in Afghanistan (14,000) than were there when he took office.

If two presidents as different as Obama and Trump, who were both intent on exiting endless wars, have so far been unable to do so, it tells you something about the difficulty of accomplishing that chimerical goal. Why is it so hard? Because there are always significant risks to removing U.S. troops from a region where the United States still maintains a significant stake.

I agree with the veteran diplomat Martin Indyk, now my colleague at the Council on Foreign Relations, that those interests are no longer as compelling as they once were, because the United States no longer needs foreign oil and Israel’s survival is no longer in question. But even Indyk, in an important Wall Street Journal essay last weekend headlined “The Middle East Isn’t Worth It Anymore” concedes that we can’t simply write off that region.

Indyk writes that we must still “deal with the remnants” of the Islamic State and al-Qaeda — a task that “can be achieved by small numbers of U.S. troops, combined with close cooperation and support for local partners.” He goes on to emphasize an even more important U.S. interest — “preventing a nuclear arms race in the Middle East.” He calls this “the one current case where the U.S. might need to resort to war,” while rightly cautioning that “we should be wary of those who would rush to battle stations.”

While I agree with Indyk on the need to downsize our objectives “in favor of more limited goals that can be achieved with more modest means,” I would be a little bit more expansive in defining those objectives. Even though we no longer need the Middle East to fuel our cars, we cannot ignore the economic significance of a region that holds nearly half of the world’s reserves of oil and natural gas. While Indyk suggests that “China and India need to be protecting the sea lanes between the Gulf and their ports, not the U.S. Navy,” we won’t be too happy if Beijing gains a stranglehold on those vital resources. As long as the U.S. Navy controls the sea lanes, Washington can threaten to shut off China’s oil — a powerful point of leverage in a crisis. (Indyk has since told me he favors joint patrols with China and India in the Persian Gulf, reducing rather than ending the U.S. role.)

U.S. interests in Africa are not as great as in the Middle East. Yet even that continent is not easy to exit. A plan to reduce the U.S. deployment to Africa — currently about 6,000 troops — has run into bipartisan opposition from members of Congress, including some Trump supporters, who argue that we must counter extremist groups and not cede influence to rivals such as China and Russia.

The number of U.S. troops deployed abroad — approximately 200,000 out of 1.3 million active-duty personnel — has already dipped to the lowest level in 60 years. But any future president will find it difficult to responsibly cut that figure any further without risking calamities such as a Taliban takeover, an Islamic State resurgence, or a nuclear arms race in the Middle East. That’s why so many of the Democratic candidates are playing word games by pledging to remove “combat troops” or “ground troops” while leaving Special Operations forces and advisers in place. Promising to end endless wars is about as meaningful a campaign promise as making Mexico pay for a border wall.

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